As a vehicular arm component, there is a suspension arm which connects a vehicle body and a wheel, and a radius rod which connects a subframe and the wheel. Such a vehicular arm component necessarily has a sufficient rigidity in order to endure a large force applied at the time when the vehicle runs or brakes while transferring a force.
As such as an arm component, for example, Patent Literature 1 discloses a suspension arm which includes a cylindrical pipe, a york portion bonded at one end in a longitudinal direction of the pipe by welding, and a bush attaching portion bonded to the other end by welding.